The present invention relates to a new and improved seat belt retractor.
Seat belt retractors store a seat belt when it is not buckled around an occupant of a vehicle. Upon the occurrence of an emergency situation while the seat belt is buckled around an occupant of a vehicle, the retractor locks the seat belt against withdrawal to restrain movement of the occupant. Known seat belt retractors include a reel around which the belt is wound. To restrain an occupant of a vehicle in an emergency situation, a locking pawl or bar is moved into engagement with ratchet wheel teeth on the reel to block rotation of the reel in an unwinding direction.
Some seat belt retractors have a pilot pawl system for moving the locking pawl into engagement with the ratchet wheel teeth. U.S. Pat. Nos. 3,834,646 and 4,475,697 disclose seat belt retractors in which a locking a pawl is moved into engagement with a ratchet wheel by a pilot pawl system. The pilot pawl system includes an inertia weight which moves a pilot pawl into engagement with a rotating pilot pawl gear upon the occurrence of excessive vehicle deceleration. The rotating pilot pawl gear continues the movement of the pilot pawl which, in turn, moves the locking pawl into engagement with the ratchet wheel. The amount of the pilot pawl gear rotation which occurs to effect movement of the locking pawl into engagement with the ratchet wheel depends upon the angular position of the teeth of the pilot pawl gear relative to the teeth of the ratchet wheel.
U.S. Pat. No. 4,101,094 discloses a pilot pawl system in which there is a clutch between the pilot pawl gear and ratchet wheel to enable the ratchet wheel to rotate relative to the pilot pawl gear. Thus, if the locking pawl does not engage the ratchet teeth, the ratchet teeth rotate relative to the pilot pawl gear and excessive forces are not applied to the pilot pawl gear or pilot pawl which might cause breaking thereof. Since relative rotation occurs between the ratchet wheel and pilot pawl gear, the angular orientation between the teeth on the pilot pawl gear and the ratchet wheel will be changed. The changed angular orientation between the teeth on the pilot pawl gear and ratchet wheel results in a different locking action being obtained the next time the retractor is actuated. Specifically, the amount of belt withdrawal will change.